Optimization of Submerged Culture Conditions for Exo-Polysaccharides Production by Streptomyces Nasri-UV 135 in Bioreactor

Abstract

Production of Exopolysaccharides "EPS" and microbial biomass by Streptomyces nasri were influenced by the type of carbon source (glycerol, xylose, fructose, galactose, glucose, mannose, sucrose, lactose, maltose, dextrin, soluble starch, corn starch and potato starch) and the nitrogen source (glycine, aspartic acid, glutamic acid, proline, ammonium sulfate, sodium nitrate and beef extract) used in the medium. Xylose and glycine were the most suitable sources of carbon and nitrogen, resp., for both production of EPS and mycelial growth. The highest EPS production was obtained in a medium containing (g/l) 30 xylose, 2.7 glycine, 4.0 NaCl, 0.5 MgSO4, 1.0 K2HPO4, and 1.0 CaCO3. Exopolysaccharides production and mycelial growth in the above suggested medium were significantly increased in a 3-l stirred tank bioreactor, where the maximum EPS concentration was 8.73 g/l, which was an approx. 1.6 time higher than that in shake culture.